JP4401707B2 - Optical transmission characteristic measurement and compensation method and apparatus using Q value and bit error rate - Google Patents

Description

  The present invention relates to an optical transmission characteristic measurement and compensation method and apparatus using a Q value and a bit error rate, and in particular, a Q value that enables high-speed operation by using the Q value and the bit error rate for optical transmission characteristic measurement. And a method and apparatus for measuring and compensating optical transmission characteristics using a bit error rate.

  Conventionally, as one of optical transmission characteristic compensation systems in an optical transmission network using an optical fiber, the following Patent Document 1 and Patent Document 2 are known regarding a system for compensating for chromatic dispersion of an optical fiber.

  That is, Patent Document 1 includes a variable dispersion equalizer in a linear repeater and a regenerative repeater arranged at a predetermined interval between a transmission device and a reception device connected via a transmission optical fiber, An automatic chromatic dispersion equalization optical transmission system is disclosed in which chromatic dispersion equalization in a linear repeater section is performed by a linear repeater, and chromatic dispersion equalization in a regenerative repeater section is performed by a receiving unit and a receiving unit of the regenerative repeater. Yes.

  Patent Document 2 discloses a monitor device for chromatic dispersion compensation that is applied to an optical communication system that has been subjected to chromatic dispersion compensation and that can simplify the configuration and reduce the number of work steps.

  Conventionally, as an optical transmission characteristic compensation system in an optical transmission network using an optical fiber, the following Patent Document 3 is known for an all-optical regeneration system.

  That is, Patent Document 3 describes a method and apparatus for realizing all-optical reproduction, and among them, a method for monitoring a Q value and a bit error rate (BER) is disclosed as an optical transmission line characteristic measurement. ing.

  Conventionally, in optical transmission networks using optical fibers, transmission characteristic compensation systems that can operate at high speed are rarely required. Therefore, Patent Documents 1 to 3 as described above describe transmission characteristics that can operate at high speed. There is no disclosure about the compensation system.

  For example, as for the chromatic dispersion compensation operation among the transmission characteristics to be compensated, the actual situation is that until now, high-speed operation has not been assumed.

  However, as a transmission characteristic compensation system capable of operating at high speed as the speed and distance of an optical transmission network using an optical fiber increase in the future, as a technique for compensating various transmission characteristics, for example, wavelength dispersion (CD: Chromatic dispersion (PMD) compensation technology, Polarization Mode Dispersion (PMD) compensation technology, signal-to-noise ratio (S / N) compensation technology, etc. are considered essential.

  Also, in the future, in an all-optical transmission network using optical fibers and a system that performs dynamic path switching control, if the transmission characteristics change due to dynamic path switching control, the transmission characteristics will change. Accordingly, it is necessary to perform transmission characteristic compensation capable of operating at higher speed as a whole system.

  In order to compensate the transmission characteristics of an optical transmission network using an optical fiber, it is necessary to grasp the transmission characteristics of the optical transmission network with high accuracy, and conventionally, a bit error rate (BER) is often used. .

  FIG. 1 is a block diagram showing a conventional transmission characteristic compensation system implemented to compensate transmission characteristics of an optical transmission network.

  This transmission characteristic compensation system includes a transmission characteristic compensation operation unit 11, a transmission characteristic measurement unit 12, and a control unit 13 in order to perform transmission characteristic compensation using feedback control.

  That is, as shown in FIG. 1, the input optical signal passes through the transmission characteristic compensation operation unit 11, and the transmission characteristic measurement unit 12 measures the transmission characteristic as a bit error rate (BER).

  A control signal for compensating the transmission characteristics is output from the control unit 13 to the transmission characteristic compensation operation unit 11 in accordance with the bit error rate (BER) measured by the transmission characteristic measurement unit 12.

  Then, an output optical signal whose transmission characteristic is compensated by the transmission characteristic compensation operation unit 11 is transmitted.

  In such a transmission characteristic compensation system, as described above, as the transmission speed increases and the transmission characteristics change at a high speed, the transmission characteristic compensation operation unit 11 and the transmission characteristic measurement unit that constitute the system. 12 and each part of the control part 13 require high-speed operation.

  However, in order to measure the bit error rate (BER) with high accuracy in the transmission characteristic measurement unit 12, a long measurement is generally performed using various error detection control techniques depending on the quality of the error rate to be measured. Time is needed.

  That is, as a measurement of the bit error rate (BER), when operating a service, in order to obtain a BER from a transmission apparatus, one is SDH: Synchronous Digital Hierarchy / SONET: Synchronous Optical Network Error detection control calculation by BIP: Bit Interleaved Parity is performed, and the bit error rate of the input optical signal is measured using the calculation result.

  In order to obtain the BER from the transmission apparatus when operating the service, the other one includes FEC: Forward Error Correction in OTU: Optical channel Transport Unit as disclosed in Non-Patent Document 1. Error detection control calculation is performed, and the bit error rate of the input optical signal is measured using the calculation result.

  Further, there is a BERT: Bit Error Rate Tester as an off-line measuring instrument for measuring BER.

  FIG. 2 is a block diagram showing a generally conceivable configuration for measuring a BER from a transmission apparatus when a service is operated in a conventional transmission system (SDH / SONET, OTU, etc.).

That is, as shown in FIG. 2, the optical signal is converted into an electrical signal by the photoelectric conversion (O / E) unit 21, and then the BER measurement unit 22 performs BIP (Bit Interleaved Parity) calculation or FEC (Forward Error Correction). An operation is performed, and the BER is measured by using the operation result.
JP 2000-115077 A JP 2001-211122 A Japanese Patent Laid-Open No. 2002-23208 ITU-TG. 709 / Y. 1331 [02/2001] pp23, 24, 63-65

By the way, in the method for measuring the bit error rate (BER) as described above, a long measurement time is required when the transmission quality is good. For example, in the case of measuring the transmission characteristics of 10 Gbit / s transmission, BER 1 × 10 ⁻¹² is set. For measurement, a measurement time of 100 sec is required at the shortest.

On the other hand, when transmission quality deteriorates, measurement is possible in a short time. For example, in the case of measuring transmission characteristics of 10 Gbit / s transmission, a measurement time of 100 msec is the shortest to measure BER1 × 10 ^−9. be able to.

  Therefore, when only the bit error rate (BER) is used for measurement of transmission characteristics, as described above, the transmission quality is good depending on the quality of the error rate to be measured using various error detection control techniques. In general, since a long measurement time is required, there is a problem in speeding up the compensation operation as the entire transmission characteristics.

  On the other hand, in order to compensate the transmission characteristics of an optical transmission network using an optical fiber, as a method of measuring with high accuracy by shortening the measurement time of the transmission characteristics in the optical transmission network, in recent years, at the research level, Q value measurement Is often used.

  This Q value measurement is a method used to solve the problem of the measurement time in the BER measurement as described above, and does not depend on whether the error rate to be measured is good or not, and in a certain relatively short measurement time. I can finish it.

  In general, for Q value measurement, an eye waveform is observed using a measuring instrument including a sampling oscilloscope, and the Q value is obtained from the observation result.

  FIG. 3 is a diagram for schematically explaining the configuration of a method for measuring the transmission characteristics of an optical signal by observing an eye waveform and measuring a Q value.

  The method of measuring the Q value by observing the eye waveform is generally directed to a research purpose.

  That is, as shown in FIG. 3, in the method of measuring the Q value by observing the eye waveform, the eye waveform is observed by an optical sampling method in which light is sampled with light using, for example, a nonlinear optical crystal or the like. A Q value calculation is performed by observing the eye waveform 30 and inputting the result to the instrument 31, and the Q value is measured using the calculation result.

  In some cases, an optical signal is O / E converted and then input to a sampling oscilloscope as the eye waveform observer 31, and the eye waveform 30 is observed to measure the Q value.

  According to such Q value measurement, in the current technology, the measurement time for Q value measurement is generally a certain time depending on the measuring device used, for example, regardless of transmission quality, for example, With a certain measuring instrument, a fixed measuring time of about 15 to 20 seconds can be achieved.

  That is, according to the Q value measurement, the better the transmission characteristics, the shorter the transmission characteristics can be measured in about 1/5 compared with the BER measurement as described above.

  On the other hand, in order to measure the transmission characteristics of the quality deteriorated by the Q value measurement, the measurement is about 100 times longer than the BER measurement as described above.

  Therefore, if only the Q value measurement is used for the measurement of the transmission characteristics, as described above, in the case of measuring the transmission characteristics with deteriorated quality, a significantly longer measurement time is required as compared with the BER measurement. There is a problem in speeding up the compensation operation as a whole of the transmission characteristics.

  Note that the measurement time required for such Q value measurement depends on the sampling rate of the measuring instrument, and it is expected that the measurement time will be shortened if the sampling rate is improved.

  However, since the measurement is performed by electrical processing inside the measuring instrument and generally requires a lot of time for electrical processing, it is expected that there is a certain limit to the improvement of the measurement time.

  In addition, the Q value measurement further requires a clock signal for measurement in the measuring instrument, and in order to solve this problem, a clock-independent measurement method has been proposed. It is expected that many measurements will be used.

  The present invention has been made in view of the above circumstances, and is measured by selectively switching between Q-value measurement and bit error rate measurement according to the transmission characteristics to be measured in the measurement and compensation of the optical transmission characteristics. It is another object of the present invention to provide an optical transmission characteristic measurement and compensation method and apparatus using a Q value and a bit error rate that enable high-speed operation of the entire transmission characteristic to be compensated.

According to the present invention, in order to solve the above problems,
(1) An optical transmission characteristic measurement and compensation method that selectively uses a Q value and a bit error rate for measurement and compensation of an optical transmission characteristic,
When "bit error rate" is used for the measurement of the optical transmission characteristics, when the optical transmission characteristics to be measured are deteriorated, the measurement time of the optical transmission characteristics is short, and the optical transmission characteristics to be measured are good Then, when the measurement time of the optical transmission characteristic becomes long and the “Q value” is used for the measurement of the optical transmission characteristic, the “bit error rate” does not depend on the quality of the optical transmission characteristic to be measured. The measurement time is longer than the measurement time when the optical transmission characteristic to be measured is deteriorated and is shorter than the measurement time when the optical transmission characteristic to be measured in the measurement of the “bit error rate” is good. Utilizing the fact that measurement time is required, when measuring the optical transmission characteristics, the optical transmission characteristics to be measured have deteriorated until the certain measurement time required for the measurement of the “Q value” is reached. In the state, When the optical transmission characteristic to be measured after reaching the certain measurement time is good, the “bit error rate” measurement is used so that the “Q value” measurement is used. And a transmission characteristic measurement step for selectively switching between the measurement of the "Q value" and the measurement of the "Q value";
A transmission characteristic compensation operation control step for controlling the compensation operation of the optical transmission characteristic to be measured by selectively using the “Q value” and the “bit error rate” measured in the transmission characteristic measurement step. ,
Q value and bit characterized in that the measurement operation of the optical transmission characteristic to be measured in the transmission characteristic measurement step and the compensation operation of the optical transmission characteristic to be measured in the transmission characteristic compensation operation control step are accelerated as a whole. An optical transmission characteristic measurement and compensation method using an error rate is provided.

(Corresponding example)
The invention (1) corresponds to the first embodiment shown in FIGS.

Further, according to the present invention, in order to solve the above problems,
(2) The transmission characteristic measurement step includes:
Maximum measurement time Max allowed for one measurement of the optical transmission characteristic Meas Incorporating errors from the measurement of time and the “bit error rate” and counting (Error count: = number of errors due to BER measurement) time (however, Wait time <Max Meas a first step of setting time);
Threshold value BER of the “bit error rate” (BER) th (however, BER th ≦ 1 / BitRate × Wait a second step of setting time),
A third step of starting the measurement of the “bit error rate” and the measurement of the “Q value” at an elapsed time of 0;
The Wait set in the first step a fourth step of waiting based on time;
The error by measuring the “bit error rate” is taken and counted (Error) count: = number of errors due to BER measurement) and the total number of errors due to BER measurement from the elapsed time 0 to the current time is obtained to obtain the BER: = Error as the “bit error rate”. a fifth step of determining count / BitRate / elapsed time;
The elapsed time <the maximum measurement time Max Meas time and said Error it is determined whether count = 0, and if so (Y), a sixth step to return to the fourth step;
If it is determined in the sixth step that it is not (N), the BER> BER a seventh step of determining whether or not th,
If it is determined in the seventh step (Y), the measurement of the “bit error rate” and the measurement of the “Q value” are terminated and transmitted as the optical transmission characteristic to be measured. Characteristic: 8th step to set as BER;
If it is determined in the seventh step that it is not (N), the measurement of the “bit error rate” is stopped, and thereafter, transmission characteristics: = Q value as the optical transmission characteristics to be measured And (9) an optical transmission characteristic measurement and compensation method using a Q value and a bit error rate according to (1).

(Corresponding example)
The invention (2) corresponds to a first embodiment shown in FIGS.

Further, according to the present invention, in order to solve the above problems,
(3) An optical transmission characteristic measurement and compensation apparatus that selectively uses a Q value and a bit error rate for measurement and compensation of an optical transmission characteristic,
When "bit error rate" is used for the measurement of the optical transmission characteristics, when the optical transmission characteristics to be measured are deteriorated, the measurement time of the optical transmission characteristics is short, and the optical transmission characteristics to be measured are good Then, when the measurement time of the optical transmission characteristic becomes long and the “Q value” is used for the measurement of the optical transmission characteristic, the “bit error rate” does not depend on the quality of the optical transmission characteristic to be measured. The measurement time is longer than the measurement time when the optical transmission characteristic to be measured is deteriorated and is shorter than the measurement time when the optical transmission characteristic to be measured in the measurement of the “bit error rate” is good. Utilizing the fact that measurement time is required, when measuring the optical transmission characteristics, the optical transmission characteristics to be measured have deteriorated until the certain measurement time required for the measurement of the “Q value” is reached. In the state, When the optical transmission characteristic to be measured after reaching the certain measurement time is good, the “bit error rate” measurement is used so that the “Q value” measurement is used. Transmission characteristic measuring means for selectively switching between measurement of "Q value" and measurement of "Q value";
Transmission characteristic compensation operation control means for controlling the compensation operation of the optical transmission characteristic to be measured by selectively using the “Q value” and the “bit error rate” measured by the transmission characteristic measurement means. ,
Q value and bit characterized by speeding up the operation of measuring the optical transmission characteristic to be measured by the transmission characteristic measuring means and the operation of compensating the optical transmission characteristic to be measured by the transmission characteristic compensation operation control means as a whole An optical transmission characteristic measurement and compensation apparatus using an error rate is provided.

(Corresponding example)
The invention (3) corresponds to the first embodiment shown in FIGS.

Further, according to the present invention, in order to solve the above problems,
(4) The transmission characteristic measuring means includes:
Maximum measurement time Max allowed for one measurement of the optical transmission characteristic Meas Incorporating errors from the measurement of time and the “bit error rate” and counting (Error count: = number of errors due to BER measurement) time (however, Wait time <Max Meas first means for setting time);
Threshold value BER of the “bit error rate” (BER) th (however, BER th ≦ 1 / BitRate × Wait a second means for setting time);
A third means for starting the measurement of the “bit error rate” and the measurement of the “Q value” at an elapsed time of 0;
The Wait set by the first means a fourth means for waiting based on time;
The error by measuring the “bit error rate” is taken and counted (Error) count: = number of errors due to BER measurement) and the total number of errors due to BER measurement from the elapsed time 0 to the current time is obtained to obtain the BER: = Error as the “bit error rate”. a fifth means for calculating count / BitRate / elapsed time;
The elapsed time <the maximum measurement time Max Meas time and said Error whether or not count = 0, and if it is determined to be (Y), sixth means for repeating the standby operation in the fourth means;
If it is determined that the sixth means does not (N), the BER> BER a seventh means for determining whether or not th is;
If the seventh means determines that this is the case (Y), the measurement of the “bit error rate” and the measurement of the “Q value” are terminated and transmitted as the optical transmission characteristic to be measured. Characteristic: = 8th means to set as BER;
If the seventh means determines that it is not (N), the measurement of the “bit error rate” is stopped, and thereafter, the transmission characteristic: = Q value as the optical transmission characteristic to be measured. And (9) an optical transmission characteristic measurement and compensation device using a Q value and a bit error rate.

(Corresponding example)
The invention (4) corresponds to Example 1 shown in FIGS. 7 and 8 described later.

Further, according to the present invention, in order to solve the above problems,
(5) The transmission characteristic measuring means includes:
A coupler that functions as an optical distributor for distributing an input optical signal;
A bit error rate measurement unit and a Q value measurement unit for measuring a bit error rate and a Q value of the input optical signal respectively input through the coupler;
An optical transmission using a Q value and a bit error rate according to (3), comprising: a CPU functioning as a transmission characteristic measurement control unit for controlling measurement operations of the bit error rate measurement unit and the Q value measurement unit A characteristic measurement and compensation device is provided.

(Corresponding example)
The invention (5) corresponds to Example 1 shown in FIGS. 7 and 8 described later.

Further, according to the present invention, in order to solve the above problems,
(6) The bit error rate measurement unit performs error detection control calculation such as BIP in SDH / SONET and FEC in OTU, and performs bit error rate measurement of the input optical signal using the calculation result. An optical transmission characteristic measurement and compensation apparatus using the Q value and the bit error rate described in (5) is provided.

(Corresponding example)
The invention (6) corresponds to Example 1 shown in FIGS. 7 and 8 described later.

Further, according to the present invention, in order to solve the above problems,
(7) The Q value measurement unit is configured to perform a Q value calculation of the input optical signal, and to perform a Q value measurement of the input optical signal using the calculation result (5) An optical transmission characteristic measurement and compensation apparatus using the described Q value and bit error rate is provided.

(Corresponding example)
The invention (7) corresponds to Example 1 shown in FIGS. 7 and 8 described later.

Further, according to the present invention, in order to solve the above problems,
(8) The transmission characteristic compensation operation control means includes:
A control selector for selectively outputting the bit error rate and Q value of the input optical signal measured by the bit error rate measuring unit and the Q value measuring unit;
A compensation operation control unit for outputting a compensation operation control signal for compensating the optical transmission characteristic to be measured based on a bit error rate and a Q value of the input optical signal selectively output from the control selector; An optical transmission characteristic measurement and compensation apparatus using a Q value and a bit error rate according to claim 5 is provided.

(Corresponding example)
The invention (8) corresponds to Example 1 shown in FIGS. 7 and 8 described later.

  According to the present invention, high-speed operation as a whole of the transmission characteristics to be measured and compensated by selectively switching between the Q value measurement and the bit error rate measurement according to the transmission characteristics to be measured when measuring the optical transmission characteristics. It is possible to provide an optical transmission characteristic compensation method and apparatus using a Q value and a bit error rate that can be realized.

  First, prior to describing an embodiment of an optical transmission characteristic measurement and compensation method using a Q value and a bit error rate according to the present invention, the basic concept of the present invention will be described.

  According to the knowledge from the prior art as described above, when the “bit error rate” is used for measurement of transmission characteristics, the measurement time in the transmission characteristic measurement unit is short (for example, 100 msec) when the transmission characteristics are deteriorated. The control and compensation operation time in the transmission characteristic compensation unit is fast.

  On the other hand, when “bit error rate” is used for measurement of transmission characteristics, when the transmission characteristics are good, the measurement time in the transmission characteristic measurement unit is long (for example, 100 sec), and the control and compensation in the transmission characteristic compensation unit Long operating time.

  For this reason, when only the “bit error rate” is used to measure the transmission characteristics, if the transmission characteristics are good and the control is performed in a short time, the transmission characteristics cannot be measured and understood sufficiently. Therefore, more optimal transmission characteristic compensation control cannot be performed.

  Further, according to the knowledge as described above, when the “Q value” is used for measurement of transmission characteristics, a certain measurement time (for example, 15 to 20 sec) is required regardless of the transmission characteristics.

  According to this "Q value" measurement, the better the transmission characteristics, the shorter the transmission characteristics can be measured in about 1/5 compared to the "bit error rate" measurement as described above. On the other hand, in order to measure the transmission characteristics of the quality deteriorated by the Q value measurement, the measurement is about 100 times longer than the “bit error rate” measurement as described above.

  For this reason, if only the “Q value” measurement is used to measure the transmission characteristics, a measurement time that is significantly longer than the “bit error rate” measurement is required when measuring transmission characteristics with degraded quality. .

  FIG. 4 is a diagram showing the relationship between the measurement time of the “bit error rate” measurement and the “Q value” measurement for schematically explaining the results based on these findings.

  In FIG. 4, the vertical axis indicates the measurement time, the horizontal axis indicates whether the transmission characteristic (quality) is good, the left side in the figure has poor transmission characteristic (quality), and the right side has good transmission characteristic (quality). It is shown that.

  That is, as shown in FIG. 4, when the “bit error rate” is used for measuring the transmission characteristic, the transmission characteristic measurement time is short (for example, 100 msec) and the transmission characteristic is good when the transmission characteristic is deteriorated. In the state, it is a characteristic curve that rises to the right so that the transmission characteristic measurement time is long (for example, 100 sec).

  In addition, as shown in FIG. 4, when the “Q value” is used for measurement of transmission characteristics, the measurement time of transmission characteristics does not depend on the transmission characteristics, and a fixed measurement time (for example, 15 to 20 sec) is required. It becomes a flat characteristic curve.

  That is, FIG. 4 shows that when the “bit error rate” is used for the measurement of the optical transmission characteristic, the measurement time of the optical transmission characteristic is short in a state where the optical transmission characteristic to be measured is deteriorated, and the optical transmission to be measured In a state where the characteristics are good, the measurement time of the optical transmission characteristics becomes long, and when the “Q value” is used for the measurement of the optical transmission characteristics, it does not depend on whether the optical transmission characteristics to be measured are good or bad. The measurement time in the state where the optical transmission characteristic to be measured is longer than the measurement time in the state where the optical transmission characteristic to be measured is deteriorated in the measurement of the “bit error rate” and the optical transmission characteristic to be measured in the measurement of the “bit error rate” is good. It shows that a certain measurement time shorter than that is required.

  Therefore, using the relationship shown in FIG. 4, in the present invention, when measuring the optical transmission characteristics, the Q value measurement and the bit error rate measurement are selectively switched according to the transmission characteristics to be measured. Therefore, it is intended to increase the speed of the entire transmission characteristic to be measured.

  FIG. 5 shows a “bit error rate” measurement and a “Q value” for schematically explaining a method of selectively switching between the Q value measurement and the bit error rate measurement according to the transmission characteristic to be measured. It is a figure which shows the relationship between the measurement time with a measurement.

  That is, according to the present invention, when measuring the optical transmission characteristic, in the state where the optical transmission characteristic to be measured until the constant measurement time required for the measurement of the “Q value” is deteriorated, the “bit error” The "bit error rate" is used so that the measurement of the "Q value" is used when the optical transmission characteristic to be measured is good after the fixed measurement time is reached. And measurement of the “Q value” are selectively switched.

Specifically, in FIG. 5, as shown by the two surrounding lines A and B, in the measurement of transmission characteristics, the ideal measurement method switching point (time) Opt on the vertical axis. meas Until a certain measurement time (for example, 15 to 20 sec) required for the “Q value” measurement as time is reached, the “bit error rate” (box A) is used to measure the transmission characteristics. Ideal measurement method switching point Opt After the BER, the switching control is performed so that the “Q value” (enclosed line B) as the recommended measurement method according to the transmission characteristic state is used for the measurement of the transmission characteristic.

Note that there is a one-to-one correspondence between the Q value and the bit error rate (BER) as shown in the following equation, and they can be replaced with each other.

  In the above equation, erf (x) is an error function.

  FIG. 6 is a diagram showing the relationship between the Q value plotted based on the above equation and the bit error rate (BER).

  As described above, in the present invention, by adopting a method of selectively switching between the Q value measurement and the bit error rate measurement according to the transmission characteristic to be measured, it is possible to achieve high-speed operation as a whole transmission characteristic to be measured. It becomes possible.

  That is, in the present invention, the transmission characteristic measuring unit is realized at high speed as a technique for performing a hybrid measurement of “bit error rate” and “Q value” in which the measurement technique is dynamically changed according to the transmission characteristics. At the same time, by performing compensation control of the transmission characteristics based on the result of measurement using a technique that can be measured at a higher speed, the transmission characteristic measurement and compensation system as a whole can be operated at high speed.

  Next, embodiments of the present invention based on the above concept will be described with reference to the drawings.

  FIG. 7 is a block diagram illustrating a configuration of a main part of the first embodiment to which the optical transmission characteristic measurement and compensation method and apparatus using the Q value and the bit error rate according to the present invention is applied.

  That is, as shown in FIG. 7, the input optical signal is transmitted through a coupler 71 that functions as an optical distributor of the transmission characteristic measurement unit 70, and a bit error rate whose measurement operation is controlled by a CPU 72 that functions as a transmission characteristic measurement control unit. The data is input to the measurement unit 73 and the Q value measurement unit 74.

  The CPU 72 of the transmission characteristic measuring unit 70 has a function of controlling a control selector 76 of the control unit 75 described later in addition to the control of the bit error rate measuring unit 73 and the Q value measuring unit 74 described above. As a result, the first to ninth steps in the transmission characteristic measurement step in the optical transmission characteristic measurement and compensation method using the Q value and the bit error rate according to the present invention are executed. An optical transmission characteristic measurement and error compensation device that uses an error rate is assumed to be a main body that executes functions as first to ninth means in transmission characteristic measurement means.

  Here, as shown in FIG. 2, the bit error rate measurement unit 73 performs error detection control calculation such as BIP in SDH / SONET and FEC in OTU, and uses the calculation result to calculate the input optical signal. Assume that the bit error rate of the signal is measured.

  Further, as shown in FIG. 3 described above, the Q value measurement unit 74 samples an optical signal with light using, for example, a non-linear optical crystal or the like in the method of measuring the Q value by observing the eye waveform. Input to an eye waveform observer using an optical sampling method, observe the eye waveform, perform Q value calculation, and use the calculation result to measure the Q value of the input optical signal And

  The Q value measuring unit 74 performs O / E conversion, inputs the optical signal to a sampling oscilloscope for eye waveform observation, observes the eye waveform, performs Q value calculation, and calculates the result. The Q value of the input optical signal can be measured using the.

  The “bit error rate” and “Q value” measured as the transmission characteristics of the input optical signal by the bit error rate measuring unit 73 and the Q value measuring unit 74 of the transmission characteristic measuring unit 70 as described above are the control unit One of the “bit error rate” and “Q value” is selected via the control signal selector 76 of 75 and is output to the compensation operation control unit 77.

  Here, the selection of the “bit error rate” and the “Q value” by the control signal selector 76 is controlled by the CPU 72 of the transmission characteristic measuring unit 70 as described above.

  The compensation operation control signal from the compensation operation control unit 77 is output to the compensation operation unit 78.

  The compensation operation unit 78 includes chromatic dispersion (CD), polarization mode dispersion (PMD), and signal-to-noise ratio as various transmission characteristics to be actually compensated by a compensation operation control signal from the compensation operation control unit 77. A compensation device for (S / N) is incorporated.

  Here, the compensation operation unit 78 has a function of receiving an input optical signal, compensating the transmission characteristic by the above-described compensation device, and transmitting an output optical signal with the compensated transmission characteristic.

  Next, the operation of the main part of the first embodiment to which the optical transmission characteristic compensation method and apparatus using the Q value and the bit error rate according to the present invention configured as described above is applied will be described.

  FIG. 8 is a flowchart for explaining the operation of the main part of the first embodiment to which the optical transmission characteristic compensation method and apparatus using the Q value and the bit error rate according to the present invention is applied.

That is, as shown in FIG. 8, first, the CPU 72 determines the maximum measurement time Max allowable for one measurement according to the user's setting. Meas Incorporating errors from the measurement of time and the “bit error rate” and counting (Error count: = number of errors due to BER measurement) time (however, Wait time <Max Meas time) is set (step S1).

Here, ideally, the maximum measurement time is equal to the ideal measurement method switching point (time) on the vertical axis of FIG. 5 described above, that is, Max. meas time: = Opt meas It is desirable to set to time.

Next, the CPU 72 determines the bit error rate (BER) threshold BER in accordance with the user setting. th (however, BER th ≦ 1 / BitRate × Wait time) is set (step S2).

  Next, the CPU 72 starts the BER measurement and the Q value measurement by the bit error rate measurement unit 73 and the Q value measurement unit 74 at the elapsed time 0 (step S3).

Next, the CPU 72 sets the Wait set in the first step. It waits based on time (step S3 ').

Next, the CPU 72 determines that the elapsed time is the maximum measurement time Max in step S5 described later. Meas The BER measurement and Q value measurement by the bit error rate measurement unit 73 and the Q value measurement unit 74 are performed until the time reaches time. Continue as needed every time.

During this time, the CPU 72 takes in the error due to the BER measurement and counts it (Error count: = number of errors due to BER measurement) and the total number of errors due to BER measurement from the elapsed time 0 to the current time is obtained, so that the bit error rate is BER: = Error. The count / BitRate / elapsed time is obtained (step S4).

Next, in step S5, the CPU 72 determines that elapsed time <maximum measurement time Max. Meas time and Error It is determined whether or not count = 0. If so (Y), the process returns to step S3 ′; otherwise (N), the process proceeds to the next step S6.

Next, in step S6, the CPU 72 determines the BER> BER. It is determined whether or not it is th. If so (Y), the process proceeds to step S7, and if not (N), the process proceeds to step S9.

In other words, the processing from step S1 to step S6 (Y) so far is the bit error rate (BER) threshold BER. The BER at that time is worse than th (Error In the case of count ≠ 0), the BER is output from the control signal selector 76 of the control unit 75 as the transmission characteristic measurement value.

  Therefore, in the case of (Y) in step S6, the CPU 72 ends the BER measurement and the Q value measurement in step S7, and sets the transmission characteristic: = BER in step S8.

In addition, the processing from step S1 to step S6 (N) is performed with a bit error rate (BER) threshold BER. BER is better than th (Error In the case of count = 0), this is a process for outputting the Q value measurement result from the control signal selector 76 of the control unit 75 as the transmission characteristic measurement value.

  Therefore, in the case of (N) in step S6, the CPU 72 stops the BER measurement in step S9, and thereafter performs a process for outputting the Q value measurement result from the control selector 76 of the control unit 75. In step S10, transmission characteristics are set as = Q value.

  Next, in step S11, the CPU 72 selectively outputs the transmission characteristics (: = BER or: = Q value) set in step S8 and step S10 from the control signal selector 76 of the control unit 75.

  The transmission characteristic (: = BER or: = Q value) selectively output from the control signal selector 76 is sent to the compensation operation control unit 77 in step S12, and the transmission characteristic compensation operation control as described below is performed. Is executed.

  In other words, the compensation operation control signal from the compensation operation control unit 77 is output to the compensation operation unit 78, and chromatic dispersion (CD) as various transmission characteristics to be compensated that are incorporated in advance in the compensation operation unit 78. Thus, a compensation operation is performed on a compensation device for compensation of polarization mode dispersion (PMD), signal-to-noise ratio (S / N), and the like.

  As a result, the input optical signal is transmitted as an output optical signal whose transmission characteristics are compensated by the above-described compensation device.

That is, according to the optical transmission characteristic measurement and compensation apparatus using the Q value and the bit error rate of the first embodiment as described above, when the “bit error rate” is used for the measurement of the optical transmission characteristic, the measurement is performed. In the state where the optical transmission characteristic to be deteriorated, the measurement time of the optical transmission characteristic is short, and in the state where the optical transmission characteristic to be measured is good, the measurement time of the optical transmission characteristic is long, and When the “Q value” is used for the measurement, it does not depend on the quality of the optical transmission characteristic to be measured, but the measurement time in the state where the optical transmission characteristic to be measured in the measurement of the “bit error rate” is deteriorated. The measurement of the optical transmission characteristics using the fact that a certain measurement time is required that is longer and shorter than the measurement time when the optical transmission characteristics to be measured in the measurement of the “bit error rate” are good. On the occasion, the “Q value” In a state where the optical transmission characteristic to be measured until the constant measurement time required for measurement is deteriorated, the measurement of the “bit error rate” is used, and the measurement after the constant measurement time is reached. In a state where the optical transmission characteristic to be measured is good, by selectively switching between the measurement of the “bit error rate” and the measurement of the “Q value” so as to use the measurement of the “Q value”, It is possible to increase the speed of the measurement operation of the optical transmission characteristic to be measured and the compensation operation of the optical transmission characteristic to be measured as a whole.

According to the first embodiment, there is provided an optical transmission characteristic measurement and compensation method that selectively uses a Q value and a bit error rate for measurement and compensation of the optical transmission characteristic. When the “bit error rate” is used, when the optical transmission characteristic to be measured is deteriorated, the measurement time of the optical transmission characteristic is short, and when the optical transmission characteristic to be measured is good, the optical transmission characteristic is When the “Q value” is used for measurement of the optical transmission characteristic because the measurement time is long, the light to be measured in the measurement of the “bit error rate” is not dependent on the quality of the optical transmission characteristic to be measured. A certain measurement time that is longer than the measurement time when the transmission characteristic is deteriorated and shorter than the measurement time when the optical transmission characteristic to be measured is good in the measurement of the “bit error rate” is required. The optical transmission using In the state where the optical transmission characteristics to be measured until the constant measurement time required for the measurement of the “Q value” is deteriorated, the measurement of the “bit error rate” is used. When the optical transmission characteristic to be measured after reaching the certain measurement time is good, the measurement of the “bit error rate” and the “Q value” are used so that the measurement of the “Q value” is used. A transmission characteristic measurement step for selectively switching between the measurement of the optical transmission characteristic, and compensation of the optical transmission characteristic to be measured by selectively using the “Q value” and the “bit error rate” measured in the transmission characteristic measurement step ; and a transmission characteristic compensation operation control step of controlling the operation, the transmission characteristic measuring the measurement should do optical transmission characteristics caused by the measurement operation and the transmission characteristic compensation operation control step of the optical transmission characteristics to the measurement by the step It is possible to realize an optical transmission characteristic measuring and compensation method using a Q value and the bit error rate, characterized in that the speed of the compensation operation as a whole of the.

In the optical transmission characteristic measurement and compensation method using the Q value and the bit error rate, preferably, the transmission characteristic measurement step includes a maximum measurement time Max allowable for one measurement of the optical transmission characteristic. Meas Incorporating errors from the measurement of time and the “bit error rate” and counting (Error count: = number of errors due to BER measurement) time (however, Wait time <Max Meas a first step of setting (time) and a threshold BER of the "bit error rate" (BER) th (however, BER th ≦ 1 / BitRate × Wait a second step of setting time), a third step of starting measurement of the “bit error rate” and a measurement of “Q value” at the elapsed time 0, and the step set in the first step Wait a fourth step of waiting based on time, and counting errors (Error) by taking in the error due to the measurement of the “bit error rate”. count: = number of errors due to BER measurement), and the total number of errors due to BER measurement from the elapsed time 0 to the current time is obtained, whereby BER: = Error is obtained as the “bit error rate”. 5th step of calculating count / BitRate / elapsed time, and elapsed time <maximum measurement time Max Meas time and said Error It is determined whether or not count = 0, and if so (Y), if it is determined in the sixth step to return to the fourth step and not so in the sixth step (N), BER> BER a seventh step for determining whether or not th, and if it is determined to be so in the seventh step (Y), the measurement of the “bit error rate” and the “Q value” When the measurement is terminated and it is determined in the eighth step that the transmission characteristic: = BER is set as the optical transmission characteristic to be measured and the seventh step is not (N), the “bit” is set. The measurement of the “error rate” is stopped, and thereafter, the transmission characteristic: = Q value is set as the optical transmission characteristic to be measured.

In addition, according to the first embodiment, an optical transmission characteristic measurement and compensation apparatus that selectively uses a Q value and a bit error rate for measurement and compensation of an optical transmission characteristic, wherein the optical transmission characteristic is measured. When the “bit error rate” is used, when the optical transmission characteristic to be measured is deteriorated, the measurement time of the optical transmission characteristic is short, and when the optical transmission characteristic to be measured is good, the optical transmission characteristic is When the “Q value” is used for measurement of the optical transmission characteristic because the measurement time is long, the light to be measured in the measurement of the “bit error rate” is not dependent on the quality of the optical transmission characteristic to be measured. A certain measurement time that is longer than the measurement time when the transmission characteristic is deteriorated and shorter than the measurement time when the optical transmission characteristic to be measured is good in the measurement of the “bit error rate” is required. The optical transmission characteristics In the state where the optical transmission characteristics to be measured until the constant measurement time required for the measurement of the “Q value” is deteriorated, the measurement of the “bit error rate” is used. When the optical transmission characteristic to be measured after reaching the certain measurement time is good, the measurement of the “bit error rate” and the “Q value” are used so that the measurement of the “Q value” is used. A transmission characteristic measuring means for selectively switching the measurement of the optical transmission characteristic, and compensation of the optical transmission characteristic to be measured by selectively using the “Q value” and the “bit error rate” measured by the transmission characteristic measuring means. A transmission characteristic compensation operation control means for controlling the operation, a measurement operation of the optical transmission characteristic to be measured by the transmission characteristic measurement means, and a compensation operation of the optical transmission characteristic to be measured by the transmission characteristic compensation operation control means As a whole Thus, it is possible to realize an optical transmission characteristic measurement and compensation apparatus using a Q value and a bit error rate that are characterized by speeding up.

In the optical transmission characteristic measurement and compensation apparatus using the Q value and the bit error rate, preferably, the transmission characteristic measurement unit is configured to allow a maximum measurement time Max allowable for one measurement of the optical transmission characteristic. Meas Incorporating errors from the measurement of time and the “bit error rate” and counting (Error count: = number of errors due to BER measurement) time (however, Wait time <Max Meas a first means for setting (time) and a threshold BER of the "bit error rate" (BER) th (however, BER th ≦ 1 / BitRate × Wait second means for setting (time), third means for starting the measurement of the “bit error rate” and the measurement of the “Q value” at the elapsed time 0, and the above-mentioned set by the first means Wait a fourth means for waiting on the basis of time, and taking in an error due to the measurement of the “bit error rate” and counting (Error count: = number of errors due to BER measurement) and the total number of errors due to BER measurement from the elapsed time 0 to the current time is obtained to obtain the BER: = Error as the “bit error rate”. fifth means for obtaining count / BitRate / elapsed time, and elapsed time <maximum measurement time Max Meas time and said Error It is determined whether or not count = 0, and if it is determined to be (Y), sixth means for repeating the standby operation in the fourth means, and the sixth If it is determined by the means that it is not (N), the BER> BER The seventh means for determining whether or not th and when the seventh means determines that it is (Y), the measurement of the “bit error rate” and the “Q value” When the measurement is terminated and the optical transmission characteristic to be measured is determined to be not so by the eighth means for setting transmission characteristic: = BER and the seventh means (N), the “bit” The measurement of the “error rate” is stopped, and thereafter, there is provided a ninth means for setting the transmission characteristic: = Q value as the optical transmission characteristic to be measured.

  FIG. 9 is a block diagram showing a configuration of a main part of the second embodiment applied to chromatic dispersion compensation as a specific example of an optical transmission characteristic measurement and compensation method and apparatus using a Q value and a bit error rate according to the present invention.

  That is, as shown in FIG. 9, the input optical signal passes through the chromatic dispersion compensation unit 92 of the transmission characteristic measurement compensation control unit 91 and has the same configuration as the transmission characteristic measurement unit 70 of FIG. Input to the functioning transmission characteristic measurement control unit 90.

  As a result, the transmission characteristic measurement control unit 90 performs the bit error rate measurement and the Q value measurement as described above, so that the BER or the Q value is selectively output to the compensation operation control unit 93 as the transmission characteristic.

  The compensation operation control signal from the compensation operation control unit 93 is output to the chromatic dispersion compensation unit 92.

  The chromatic dispersion compensation unit 92 incorporates a compensation device for compensating chromatic dispersion (CD) as a transmission characteristic to be actually compensated by a compensation operation control signal from the compensation operation control unit 93.

  Here, the chromatic dispersion compensator 92 has a function of receiving an input optical signal and transmitting an output optical signal in which the chromatic dispersion (CD) is compensated by the compensation device for compensating the chromatic dispersion (CD) described above. is doing.

  As described above, according to the second embodiment, it is possible to increase the speed of the control operation in the chromatic dispersion compensation.

  In other words, with respect to the chromatic dispersion compensation technique, there are conventional methods for controlling using the error rate and the Q value. However, in these methods, there is a problem when the characteristics of the transmission path are slow. However, when dynamic transmission line switching occurs in the future, and high-speed compensation of chromatic dispersion compensation is required at that time, transmission characteristic measurement compensation by feedback control as in the second embodiment of the present invention By using the control unit 91, a high-speed compensation operation can be realized.

  As a result, it is possible to shorten the time to line setting (time to optimally compensate for chromatic dispersion) at the start of transmission line service.

  Note that the chromatic dispersion compensation method as in the second embodiment can be similarly applied to polarization mode dispersion (PMD) compensation that affects transmission characteristics, and high speed with respect to polarization mode dispersion (PMD). Compensation control can be realized.

  FIG. 10 is a block diagram showing the configuration of the main part of the third embodiment applied to optimization control of an all-optical regeneration system as a specific example of an optical transmission characteristic compensation method and apparatus using the Q value and bit error rate according to the present invention. It is.

  That is, as shown in FIG. 10, the input optical signal passes through the all-optical regeneration system 102 of the transmission characteristic measurement compensation control unit 101 and has the same configuration as the transmission characteristic measurement unit 70 of FIG. Input to the functioning transmission characteristic measurement control unit 100.

  Thereby, in the transmission characteristic measurement control unit 100, the bit error rate measurement and the Q value measurement are performed as described above, whereby the BER or the Q value is selectively output to the compensation operation control unit 103 as the transmission characteristic.

  The compensation operation control signal from the compensation operation control unit 103 is output to the all-optical reproduction system 102.

  In this all-optical regeneration system 102, the compensation operation control signal from the compensation operation control unit 103 is used to determine the operation conditions of each device in all-optical regeneration (voltage, current, optical A compensation device for performing optimization control of power adjustment is incorporated.

  The all-optical regeneration system 102 receives an input optical signal and determines the operating conditions of each device in the all-optical regeneration (adjustment of the voltage, current, and optical power of each device) according to the transmission characteristics to be actually compensated. It has a function of transmitting an output optical signal subjected to optimization control.

  As described above, according to the third embodiment, it is possible to speed up the control operation in the all-optical regeneration system.

  That is, at present, many optical regeneration technologies have been proposed for realizing an all-optical regeneration system including an all-optical 2R system and an all-optical 3R system. In such an all-optical regeneration system, each device in all-optical regeneration has been proposed. Although it is necessary to perform optimization control of operation conditions (adjustment of voltage, current, and optical power of each device), the transmission characteristic measurement compensation control unit 101 by feedback control as in the third embodiment of the present invention is applied. Thus, it is possible to realize high-quality transmission characteristics with a short control time during optimization.

  As described above, according to the second and third embodiments of the present invention, the transmission characteristic measurement is speeded up by realizing the high-speed transmission characteristic compensation by the hybrid control using the error rate and the Q value. As a result, the entire system can be operated at high speed.

  Further, according to the second and third embodiments of the present invention, it is possible to reduce the data error and the service stop time by increasing the speed of the transmission characteristic compensation.

FIG. 1 is a block diagram showing a conventional transmission characteristic compensation system implemented to compensate transmission characteristics of an optical transmission network. FIG. 2 is a block diagram showing a generally conceivable configuration for measuring a BER from a transmission apparatus when a service is operated in a conventional transmission system (SDH / SONET, OTU, etc.). FIG. 3 is a diagram for schematically explaining the configuration of a method for measuring the transmission characteristics of an optical signal by observing an eye waveform and measuring a Q value. FIG. 4 is a diagram showing the relationship between the measurement time of the “bit error rate” measurement and the “Q value” measurement for schematically explaining the result based on the knowledge from the prior art. FIG. 5 shows a “bit error rate” measurement and a “Q value” for schematically explaining a method of selectively switching between the Q value measurement and the bit error rate measurement according to the transmission characteristic to be measured. It is a figure which shows the relationship between the measurement time with a measurement. FIG. 6 is a diagram illustrating the relationship between the Q value and the bit error rate (BER). FIG. 7 is a block diagram illustrating a configuration of a main part of the first embodiment to which the optical transmission characteristic measurement and compensation method and apparatus using the Q value and the bit error rate according to the present invention is applied. FIG. 8 is a flowchart for explaining the operation of the main part of the first embodiment to which the optical transmission characteristic measurement and compensation method and apparatus using the Q value and the bit error rate according to the present invention is applied. FIG. 9 is a block diagram showing a configuration of a main part of the second embodiment applied to chromatic dispersion compensation as a specific example of an optical transmission characteristic measurement and compensation method and apparatus using a Q value and a bit error rate according to the present invention. FIG. 10 shows the configuration of the main part of the third embodiment applied to the optimization control of the all-optical regeneration system as a specific example of the optical transmission characteristic measurement and compensation method and apparatus using the Q value and the bit error rate according to the present invention. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Transmission characteristic compensation operation | movement part, 12 ... Transmission characteristic measurement part, 13 ... Control part,
21 ... Photoelectric conversion (O / E) unit, 22 ... BER measurement unit, 31 ... Eye waveform observation device,
30 ... Eye waveform, 70 ... Transmission characteristic measuring unit, 71 ... Coupler functioning as optical distributor,
72... CPU functioning as a transmission characteristic measurement control unit, 73... Bit error rate measurement unit,
74 ... Q value measurement unit, 75 ... control unit, 76 ... control signal selector, 77 ... compensation operation control unit, 78 ... compensation operation unit, 91 ... transmission characteristic measurement compensation control unit, 92 ... chromatic dispersion compensation unit,
DESCRIPTION OF SYMBOLS 90 ... Transmission characteristic measurement control part, 93 ... Compensation operation | movement control part, 101 ... Transmission characteristic measurement compensation control part, 102 ... All-optical reproduction | regeneration system, 100 ... Transmission characteristic measurement control part, 103 ... Compensation operation | movement control part.

Claims (8)

An optical transmission characteristic measurement and compensation method that selectively uses a Q value and a bit error rate for measurement and compensation of an optical transmission characteristic,
When "bit error rate" is used for the measurement of the optical transmission characteristics, when the optical transmission characteristics to be measured are deteriorated, the measurement time of the optical transmission characteristics is short, and the optical transmission characteristics to be measured are good Then, when the measurement time of the optical transmission characteristic becomes long and the “Q value” is used for the measurement of the optical transmission characteristic, the “bit error rate” does not depend on the quality of the optical transmission characteristic to be measured. The measurement time is longer than the measurement time when the optical transmission characteristic to be measured is deteriorated and is shorter than the measurement time when the optical transmission characteristic to be measured in the measurement of the “bit error rate” is good. Utilizing the fact that measurement time is required, when measuring the optical transmission characteristics, the optical transmission characteristics to be measured have deteriorated until the certain measurement time required for the measurement of the “Q value” is reached. In the state, When the optical transmission characteristic to be measured after reaching the certain measurement time is good, the “bit error rate” measurement is used so that the “Q value” measurement is used. And a transmission characteristic measurement step for selectively switching between the measurement of the "Q value" and the measurement of the "Q value";
A transmission characteristic compensation operation control step for controlling the compensation operation of the optical transmission characteristic to be measured by selectively using the “Q value” and the “bit error rate” measured in the transmission characteristic measurement step. ,
Q value and bit characterized in that the measurement operation of the optical transmission characteristic to be measured in the transmission characteristic measurement step and the compensation operation of the optical transmission characteristic to be measured in the transmission characteristic compensation operation control step are accelerated as a whole. Optical transmission characteristic measurement and compensation method using error rate. The transmission characteristic measurement step includes:
Maximum measurement time Max allowed for one measurement of the optical transmission characteristic Meas Incorporating errors from the measurement of time and the “bit error rate” and counting (Error count: = number of errors due to BER measurement) time (however, Wait time <Max Meas a first step of setting time);
Threshold value BER of the “bit error rate” (BER) th (however, BER th ≦ 1 / BitRate × Wait a second step of setting time),
A third step of starting the measurement of the “bit error rate” and the measurement of the “Q value” at an elapsed time of 0;
The Wait set in the first step a fourth step of waiting based on time;
The error by measuring the “bit error rate” is taken and counted (Error) count: = number of errors due to BER measurement) and the total number of errors due to BER measurement from the elapsed time 0 to the current time is obtained to obtain the BER: = Error as the “bit error rate”. a fifth step of determining count / BitRate / elapsed time;
The elapsed time <the maximum measurement time Max Meas time and said Error it is determined whether count = 0, and if so (Y), a sixth step to return to the fourth step;
If it is determined in the sixth step that it is not (N), the BER> BER a seventh step of determining whether or not th,
If it is determined in the seventh step (Y), the measurement of the “bit error rate” and the measurement of the “Q value” are terminated and transmitted as the optical transmission characteristic to be measured. Characteristic: 8th step to set as BER;
If it is determined in the seventh step that it is not (N), the measurement of the “bit error rate” is stopped, and thereafter, transmission characteristics: = Q value as the optical transmission characteristics to be measured 9. The optical transmission characteristic measurement and compensation method using a Q value and a bit error rate according to claim 1, further comprising: An optical transmission characteristic measurement and compensation apparatus that selectively uses a Q value and a bit error rate for measurement and compensation of an optical transmission characteristic,
When "bit error rate" is used for the measurement of the optical transmission characteristics, when the optical transmission characteristics to be measured are deteriorated, the measurement time of the optical transmission characteristics is short, and the optical transmission characteristics to be measured are good Then, when the measurement time of the optical transmission characteristic becomes long and the “Q value” is used for the measurement of the optical transmission characteristic, the “bit error rate” does not depend on the quality of the optical transmission characteristic to be measured. The measurement time is longer than the measurement time when the optical transmission characteristic to be measured is deteriorated and is shorter than the measurement time when the optical transmission characteristic to be measured in the measurement of the “bit error rate” is good. Utilizing the fact that measurement time is required, when measuring the optical transmission characteristics, the optical transmission characteristics to be measured have deteriorated until the certain measurement time required for the measurement of the “Q value” is reached. In the state, When the optical transmission characteristic to be measured after reaching the certain measurement time is good, the “bit error rate” measurement is used so that the “Q value” measurement is used. Transmission characteristic measuring means for selectively switching between measurement of "Q value" and measurement of "Q value";
Transmission characteristic compensation operation control means for controlling the compensation operation of the optical transmission characteristic to be measured by selectively using the “Q value” and the “bit error rate” measured by the transmission characteristic measurement means. ,
Q value and bit characterized by speeding up the operation of measuring the optical transmission characteristic to be measured by the transmission characteristic measuring means and the operation of compensating the optical transmission characteristic to be measured by the transmission characteristic compensation operation control means as a whole Optical transmission characteristic measurement and compensation device using error rate. The transmission characteristic measuring means includes
Maximum measurement time Max allowed for one measurement of the optical transmission characteristic Meas Incorporating errors from the measurement of time and the “bit error rate” and counting (Error count: = number of errors due to BER measurement) time (however, Wait time <Max Meas first means for setting time);
Threshold value BER of the “bit error rate” (BER) th (however, BER th ≦ 1 / BitRate × Wait a second means for setting time);
A third means for starting the measurement of the “bit error rate” and the measurement of the “Q value” at an elapsed time of 0;
The Wait set by the first means a fourth means for waiting based on time;
The error by measuring the “bit error rate” is taken and counted (Error) count: = number of errors due to BER measurement) and the total number of errors due to BER measurement from the elapsed time 0 to the current time is obtained to obtain the BER: = Error as the “bit error rate”. a fifth means for calculating count / BitRate / elapsed time;
The elapsed time <the maximum measurement time Max Meas time and said Error whether or not count = 0, and if it is determined to be (Y), sixth means for repeating the standby operation in the fourth means;
If it is determined that the sixth means does not (N), the BER> BER a seventh means for determining whether or not th is;
If the seventh means determines that this is the case (Y), the measurement of the “bit error rate” and the measurement of the “Q value” are terminated and transmitted as the optical transmission characteristic to be measured. Characteristic: = 8th means to set as BER;
If the seventh means determines that it is not (N), the measurement of the “bit error rate” is stopped, and thereafter, the transmission characteristic: = Q value as the optical transmission characteristic to be measured. 9. An optical transmission characteristic measuring and compensating apparatus using a Q value and a bit error rate according to claim 3, further comprising: ninth means for setting The transmission characteristic measuring means includes
A coupler that functions as an optical distributor for distributing an input optical signal;
A bit error rate measurement unit and a Q value measurement unit for measuring a bit error rate and a Q value of the input optical signal respectively input through the coupler;
4. An optical transmission using a Q value and a bit error rate according to claim 3, further comprising a CPU functioning as a transmission characteristic measurement control unit for controlling measurement operations of the bit error rate measurement unit and the Q value measurement unit. Characteristic measurement and compensation device.   The bit error rate measurement unit is configured to perform error detection control calculation such as BIP in SDH / SONET and FEC in OTU, and to measure the bit error rate of the input optical signal using the calculation result. The optical transmission characteristic measurement and compensation apparatus using the Q value and the bit error rate according to claim 5.   The said Q value measurement part is comprised so that Q value calculation of the said input optical signal may be performed, and Q value measurement of the said input optical signal may be performed using the calculation result. Optical transmission characteristic measurement and compensation apparatus using Q value and bit error rate. The transmission characteristic compensation operation control means includes
A control selector for selectively outputting the bit error rate and Q value of the input optical signal measured by the bit error rate measuring unit and the Q value measuring unit;
A compensation operation control unit for outputting a compensation operation control signal for compensating the optical transmission characteristic to be measured based on a bit error rate and a Q value of the input optical signal selectively output from the control selector; The optical transmission characteristic measurement and compensation apparatus using the Q value and the bit error rate according to claim 5.

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